NOAA Technical Memorandum NMFS-AFSC-145
 
 

Aerial Surveys of Beluga Whales 

in Cook Inlet, Alaska, 

Between June 2001 and June 2002 

by 

D. J. Rugh, B. A. Mahoney, and B. K. Smith 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

Alaska Fisheries Science Center 

July 2004 
NOAA Technical Memorandum NMFS 

The National Marine Fisheries Service's Alaska Fisheries Science Center 

uses the NOAA Technical Memorandum series to issue informal scientific and 

technical publications when complete formal review and editorial processing 

are not appropriate or feasible. Documents within this series reflect sound 

professional work and may be referenced in the formal scientific and technical 

literature. 

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries 

Science Center continues the NMFS-F/NWC series established in 1970 by the 

Northwest Fisheries Center. The NMFS-NWFSC series is currently used by 

the Northwest Fisheries Science Center. 

This document should be cited as follows: 

Rugh, D. J., B. A. Mahoney, and B. K. Smith. 2004. Aerial surveys of 

beluga whales in Cook Inlet, Alaska, between June 2001 and June 

2002. U. S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-145, 

26 p. 

Reference in this document to trade names does not imply endorsement by 

the National Marine Fisheries Service, NOAA. 
NOAA Technical Memorandum NMFS-AFSC-145
 
 

Aerial Surveys of Beluga Whales 

in Cook Inlet, Alaska, 

Between June 2001 and June 2002 

by 1 2

D. J. Rugh, B. A. Mahoney, and B. K. Smith2 

1 

National Marine Mammal Laboratory 

Alaska Fisheries Science Center 

7600 Sand Point Way N.E. 

Seattle, WA 98115 

www.afsc.noaa.gov 

2

Alaska Regional Office 

222 W. 7th Ave., Box 43 

Anchorage, AK 99513 

U.S. DEPARTMENT OF COMMERCE 

Donald L. Evans, Secretary 

National Oceanic and Atmospheric Administration 

Vice Admiral Conrad C. Lautenbacher, Jr., U.S. Navy (ret.), Under Secretary and Administrator 

National Marine Fisheries Service 

William T. Hogarth, Assistant Administrator for Fisheries 

July 2004 
This document is available to the public through: 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

www.ntis.gov 
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iii 

Abstract 

The National Marine Fisheries Service (NMFS) conducted aerial surveys of the beluga whale 

(Delphinapterus leucas) population in Cook Inlet, Alaska, almost monthly between June 2001 and 

June 2002. The surveys were flown in a twin-engine, high-wing aircraft at an altitude of 244 m (800 

ft) and speed of 185 km/hour (100 kt). Tracklines were approximately 1.4 km offshore, and 

systematic transects were made across the inlet, covering much of upper Cook Inlet. These methods 

were consistent with NMFS= abundance surveys conducted each June or July since 1993, except that 

only in June were there multiple surveys (repeat samplings) within a block of days. During the 2001-

02 monthly surveys, aerial counts of belugas (median counts when more than one observer was 

counting) generally stayed high from June through October (n = 211 in June, 39 and 152 in July, 205 

in August, 185 in September, 162 in October, respectively), but counts dropped from November to 

April (n = 24 in November, 15 in January, 0 in February, 18 in April, respectively) before rising again 

the following June (n = 192). Low counts in winter were probably due to ice in the inlet, making it 

hard to see the white whales. This study provides evidence of the presence of belugas in upper Cook 

Inlet in nearly every month of the year, but it is not clear what proportion of the population remains in 

the upper inlet year-round. 
v 

Contents 

Abstract .................................................................... iii 


Introduction .................................................................. 1

Methods ..................................................................... 2

Study Area ............................................................. 2

Survey Procedure ........................................................ 2

Counting Protocol ....................................................... 3

Results ...................................................................... 4

Survey Effort ........................................................... 4

Daily Reports ........................................................... 5

2 July 2001 ....................................................... 5

26-27 July 2001 ................................................... 6

27 August 2001 ................................................... 6

15 and 18 September 2001 ...........................................7


12 and 15 October 2001 ............................................. 8

8-9 November 2001 ................................................ 8

22-23 January 2002 ................................................ 9

25-26 February 2002 ............................................... 9

2-3 April 2002 .................................................... 9

Summary Counts of Belugas .............................................. 10 


Summary of Sighting Distributions ......................................... 11 


Other Marine Mammals .................................................. 12 


Discussion .................................................................. 12 


Acknowledgments ............................................................ 13 


Citations .................................................................... 14 

Introduction 

Each June or July since 1993, the National Marine Fisheries Service (NMFS) has 

conducted annual aerial surveys to document the distribution and abundance of belugas 

(Delphinapterus leucas) in Cook Inlet (Withrow et al. 1994; Rugh et al. 1995, 1996, 1997a, 

1997b, 1999, 2000a, 2001, 2002, 2003). The small size of this beluga stock (approximately 350 

whales; Hobbs et al. 2000a) and their isolation from other stocks (O=Corry-Crowe et al. 1997; 

Laidre et al. 2000; Rugh et al. 2000b) has raised concerns about the management of this 

population. On 31 May 2000, this stock was designated as depleted under the Marine Mammal 

Protection Act (65 FR 34590). A small, regulated harvest by Alaska Native has continued. 

As a part of the research to help reach management goals, it has proved important to 

establish where the Cook Inlet stock of belugas are throughout the year, not just in June or July 

when all of the abundance surveys have been conducted. The winter distribution has been an 

issue raised by local Natives (Huntington 2000), and establishing whether the whales use upper 

Cook Inlet year-round may play an important role in identifying and protecting appropriate 

habitat. Accordingly, the current study was designed to survey beluga distribution in upper 

Cook Inlet (north of East and West Forelands) every 1-2 months between the annual abundance 

surveys conducted in June 2001 (Rugh 2002a) and June 2002 (Rugh 2002b). The intent was to 

keep the search effort as consistent as possible with the previous surveys, except the emphasis 

would be on beluga distribution, not abundance, reducing the need for multiple counts across 

several days. 
Methods 

Study Area 

Cook Inlet is a major marine feature in south-central Alaska with 1,350 km of shoreline 

and a surface area of approximately 20,000 km2. The aerial surveys in this study covered the 

northern half of Cook Inlet, an area in which nearly all belugas have been seen in the recent past 

(Rugh et al. 2000b). A description of beluga habitat in Cook Inlet can be found in Moore et al. 

(2000). Inlet waters in this area are extremely turbid, and during winter there are extensive areas 

of ice coverage. Both factors, especially sea ice, can make it difficult to see whales. Anchorage 

served as the base of operations for these aerial surveys. 

Survey Procedure 

The survey aircraft (also used during the abundance surveys, an Aero Commander 680 

FLP) has twin-engines, high-wings, and 10-hour flying capability. There are bubble windows at 

each of the three observer positions (two on the left and one on the right). An intercom system 

provided communication among the three observers, data recorder, and pilot. Location data 

were collected from the aircraft=s global positioning system (GPS) interfaced with the laptop 

computer used to enter sighting data. Data entries included routine updates of time, locations (at 

least once per minute), percent cloud cover, sea state (Beaufort scale), glare (on the left and 

right), visibility (on the left and right), and ice conditions (percent ice cover within the 

immediate viewing area). Visibility was documented in five subjective categories from excellent 

to useless; conditions rated poor or useless were considered unsurveyed. Flight dates were a 

function of availability of aircraft and crew. Timing of flights was a compromise between 
3 

surveying the respective areas at low tide and flying during hours when light levels were 

optimal. At low tide, there is less surface area to search because of the extensive tidal flats near 

the Susitna rivers, Knik Arm, and Turnagain Arm, and belugas tend to form tighter groups. 

The surveys along the coast were generally conducted 1.4 km offshore (10E below 

horizontal while the aircraft was at the standard altitude of 244 m (800 ft)), as is done during the 

June surveys (Rugh et al. 2000b). Ground speed was approximately 185 km/hour (100 knots). 

Systematic transects were also flown across the inlet following a Asawtooth@ pattern that 

provided an efficient and thorough coverage of most areas north of Kalgin Island. 

Counting Protocol 

When a beluga group was seen, the sighting was reported immediately to the data 

recorder. Subsequently, the aircraft left the trackline to begin a series of counting passes over 

the group. These passes were on extended ovals with the counts done along the longitudinal 

axes; turns were made well beyond the ends of the group. Counts began and ended on a cue 

from the front observer, starting when the leading edge of the group was close enough to be 

counted and ending when the trailing edge went behind the wing line. The observers wrote 

down their counts along with date, time, pass number, and quality of the count. The quality of a 

count was a function of how well the observers saw the location of a group, not how many 

whales were at the surface on the respective pass. Ratings were A (if no glare, whitecaps, or 

distance compromised the counting effort) through F (if it was not practical to count whales on 

that pass). Only quality A and B estimates were used in the analysis. Only whales that were at 

the surface during the counting period were included; whale tracks or ripples in the muddy water 
4 

were not counted. There was little confusion as to whether or not a whale was at the surface 

because the water was opaque within a few centimeters. As in the June surveys, a video camera 

documented whale groups, providing images that could later be analyzed in the laboratory. 

All aerial counts were made by the two primary observers (Mahoney and Smith). In the 

analysis, each observer=s counts were sorted by the respective whale group, and a median was 

taken of the multiple counts for each group. The average of the two observer=s medians provided 

an approximation of relative group size, albeit without corrections for whales totally underwater 

and out of sight during the count or whales that were missed even though at the surface. 

Corrections for missing whales were only done to calculate abundance estimates made from the 

June surveys (Hobbs et al. 2000a, 2000b) because only one survey was made through the area 

during the monthly flights, and there was no independent search effort. The medians used here 

are calculated in the same manner as is done for the annual index counts (e.g., Rugh et al. 

2000b). 

Results 

Survey Effort 

Between June 2001 and June 2002, there were flights on 16 days representing 9 survey 

periods generally 3 weeks apart (Table 1). Daily flight duration (total time = 81.4 hours) ranged 

from 3 to 10 hours per day, all based out of Anchorage. Systematic search effort was conducted 

for a total of 63.6 hours across this period (78% of the effective search time), not including time 

spent deadheading without a search effort, circling whale groups, or periods with poor visibility 

(as determined by the left-front observer). Of the two primary observers, Smith has flown with 
5 

this project three times in the past, and Mahoney has participated in all but one season since the 

project began in 1993. Each of these surveys provided a thorough coverage of most coastal 

areas of upper Cook Inlet and much of the offshore areas (Figs. 1-9). 

Daily Reports 

2 July 2001 - - This survey followed the standard pattern of flying from Anchorage 

(starting from south and east of the city) to Point Possession and on to East Foreland, then across 

the inlet to West Foreland and north to Beluga River where a group of belugas was found. At 

this point, a quick flight was made back to Anchorage to correct a computer problem; the survey 

then picked up again at Beluga River. From there, the survey continued north and east along the 

shore to Point MacKenzie and into Knik Arm as far as Birchwood Airport. After Knik, the 

survey went around Anchorage and into Turnagain Arm, then to Chickaloon Bay. When the 

coastal track was complete, the survey continued with a series of transects across the inlet as far 

south as Kasilof and Drift Rivers (Fig. 1). 

Although survey coverage was thorough and visibility was generally good to excellent, 

large groups of belugas were not found on this day. Three groups were seen in the Susitna River 

area (at Beluga River, east of the Susitna River, and at the mouth of the Susitna River), and one 

group was near Point Possession, but none of these groups were large. The total count for this 

day (n = 39; Table 2) was only 18% of the index count for the abundance survey in June (n = 

211 whales; Rugh et al. 2002a). Officers from the NMFS Office of Enforcement/Alaska 

Division also flew a survey on 2 July from Point MacKenzie to Tyonek and found only one 

group of two belugas at the Beluga River. Note that during the systematic surveys in June, there 
6 

are also days when large groups of whales are missed (see section on Summary Counts of 

Belugas). 

26-27 July 2001 - - On the first day (26 July), straight-line transects were flown across 

the inlet as far south as Harriet Point (Fig. 2), but much of the west side of the inlet south of 

West Foreland was obscured by low clouds/fog. Helicopter traffic near the oil rigs made it too 

hazardous to survey in these conditions. Visibility was excellent in some areas with calm 

waters, but conditions deteriorated to poor in other areas due to low clouds, which sometimes 

forced the plane to fly as low as 300 ft. One group of belugas was seen near the Susitna River 

(Table 2). On the second day (27 July), a standard coastal survey was flown. Visibility was 

generally good to excellent. Belugas were found near the Little Susitna River and near Eagle 

Bay in Knik Arm (Table 2; Fig. 2). The summary count (n = 152; Table 1) was 59 less than the 

standardized median counts (n = 211) done in the June surveys, but it was within the range of the 

daily counts (n = 78-208) from June 2001 and June 2002 (Rugh et al. 2002a, 2002b). 

27 August 2001 - - Both coastal and straight-line transects were flown on the same day 

(Fig. 3). Weather was good, allowing for a thorough coverage of the survey area from Kalgin 

Island north, although rain reduced the search near Kenai. Two beluga groups were found in 

Turnagain Arm. One group was near the mouth of Little Susitna River. In Knik Arm, one group 

was near Anderson Dock and another northeast of Eagle Bay (Table 2). A lone beluga was seen 

in the middle of the inlet north of West and East Forelands. This whale appeared to have a tag, 

and at that time a tagged whale (DL-01-06; NMFS unpubl. data) was in the same area. Because 
7 

the whale was alone, it was not considered to be representative of the beluga distribution during 

late August. All of the other whale sightings made on this flight were in groups of 3-83 whales 

by aerial count and were in locations more typical of their summer distribution (Table 2). In 

August, 50-75% of the tagged whale records (n = 7 belugas) were in Knik Arm, the rest were 

near the Little Susitna River or to the east in or near Turnagain Arm. 

15 and 18 September 2001 - - A standard coastal survey was flown under mostly 

excellent or good conditions (Fig. 4). Three groups of whales were seen in Knik Arm, one with 

more than 100 whales (Table 2). Another large group was found in Turnagain Arm. Only single 

whales were found near the Beluga and Theodore Rivers. The summary median count for this 

day (n = 185; Table 1) was only 26 less than the median count (n = 211) from the intensive 

abundance survey done in June, three months earlier, and these September counts were in the 

middle of the range of the daily counts (n = 98-208) made in June; Rugh et al. 2002a). 

Although a transect flight could not be paired with the 15 September coastal survey until 

3 days later, the generalized consistency of the beluga distribution during such a time frame 

(Rugh et al. 2000b) allowed us to consider the coastal survey on 15 September and the transects 

on 18 September as representing the same distribution. Several belugas were seen near the Little 

Susitna River prior to starting the transects, but no whales were seen while flying on transects. 

All of the standard transects were flown. A low cloud ceiling (sometimes forcing the aircraft to 

fly at 500 ft), scattered fog, and some whitecaps compromised visibility during parts of this 

survey, but only fair or better conditions are reflected in the flight tracklines in Figure 4. 
8 

12 and 15 October 2001 -- Transects were flown on 12 October with good coverage of 

all lines (Fig. 5). Visibility was good to excellent throughout the survey. No whales were seen 

while on transects, but a group of belugas was seen near the Little Susitna River after the 

transects were completed (Table 2). A boat was approaching the whales until the aircraft began 

circling the area, after which the whales were not seen again. 

The coastal survey could not be flown until 15 October. Coverage for the coastal survey 

was thorough with mostly good to excellent conditions. All of the beluga sightings were in Knik 

Arm. The sum of the counts from the coastal survey (n = 162; Table 1) is about 50 whales less 

than the median counts from the intensive surveys in June, but it is well within the range of the 

daily counts in June (n = 98-208; Rugh et al. 2002a), which meant that in October most of the 

whales were still in upper Cook Inlet. 

8-9 November 2001 -- Standard transects were flown on 8 November (Fig. 6). Ice 

covered much of the area except in the middle of the inlet. Generally, visibility was fair or good, 

but no belugas were seen. 

A thorough coastal survey was flown on 9 November (Fig. 6) with mostly good to 

excellent conditions, but ice did compromise the search effort, especially in the Susitna Delta, 

Turnagain Arm, and parts of Knik Arm, areas where belugas are usually found on summer 

surveys. Two small groups were seen in Turnagain Arm, 1-2 whales were in Trading Bay, and a 

few whales were seen in Knik Arm (Table 2), but the summary count (n = 24; Table 1) was only 

11% of the index count made in June. 
9 

Except for the 1-2 whales in Trading Bay, the sighting distribution was typical of where 

whales have been seen in upper Cook Inlet in the summer (Rugh et al. 2000; 2002b). 

22-23 January 2002 - - Transects were flown on 22 January with good viewing 

conditions until fog was encountered near Kenai (Fig. 7). Areas north of Trading Bay were 

generally 50-100% ice-covered with large areas of ice south of there as well. In spite of the 

widespread ice, five small groups of belugas were seen (Table 2), all of them in a tight 

concentration west of Moose Point, well away from shore (Fig. 7). 

On 23 January, during the coastal survey, no whales were seen. Much of the area was 

ice-covered, making it difficult to find whales. The coastal survey followed the same route used 

during open-water periods. 

25-26 February 2002 -- Standard transects were flown on 25 February and a coastal 

survey on 26 February (Fig. 8). Visibility ranged from poor to good. Ice was extensive across 

much of the inlet north of Trading Bay, with large areas of ice south of there as well. However, 

some areas B such as south of the Susitna River B were almost ice free. No whales were seen 

during either of the flights in February. 

2-3 April 2002 -- On 2 April, the full array of offshore transects were conducted, and on 

3 April a thorough coastal survey was flown (Fig. 9). Viewing conditions ranged from fair to 

excellent. Ice was extensive in some areas, as with the winter surveys, and few whales were 
10 

found (Table 2). The distribution of sightings in April was very similar to the distribution in 

January with a few small groups seen west of Point Possession. 

Summary Counts of Belugas 

Medians of counts of belugas are presented in Table 1, and sighting locations are shown 

in Figures 1-9. The counts from July to October were similar to the counts in June, except for 

one low count in early July; however, counts were consistently low from November to April. 

The single-sample approach used during this study of seasonal distribution was more 

efficient than flying each area many times (as is done during the abundance surveys in June), but 

a single flight through an area means observers are more vulnerable to missing major groups, 

resulting in low counts such as on 2 July (Table 1). By comparison, during the intensive 

abundance surveys, flights are made across the same area on several different days, producing 

multiple samples, primarily as a test of variance. These samples can produce repeatable results; 

for instance, on 5 of 6 days during the June 2001 survey, median counts in the Susitna/Knik Arm 

area only ranged from 67 to 97 (one day the count was 181; Rugh et al. 2002a), and in June 2002 

in the same area, 5 of 6 counts were 131 to 175 (one count was 98; Rugh et al. 2002b). 

However, if one large group is missed, the counts can be drastically lower, which probably 

explains the low count in July 2001. 

Counts made from videotapes collected on the respective flights are presented in Table 2 

whenever video images were of sufficient quality for counting. When multiple video counts 

were made for a group, only the median is shown in Table 2. There were no significant 

differences (P > 0.60; Table 3) between counts made by the two observers in the aircraft relative 
11 

to the video counts for the same aerial pass. Similar results were obtained when comparing 

video counts to the same observers= aerial counts in June 2001 and June 2002 (P > 0.25; Table 

3). 

There was no attempt in this study to assess total abundance as is done annually during 

the June surveys (Hobbs et al. 2000a) because the objective of the project was to assess beluga 

distribution through many months of surveying rather than attempting abundance estimates 

through multiple samples within a short season. Medians of multiple aerial counts were used 

here (e.g., Table 1) as an indication of relative group sizes to best depict whale distribution. 

Summary of Sighting Distributions 

These monthly surveys in upper Cook Inlet resulted in beluga sighting distributions 

generally similar to those recorded during the abundance surveys in June/July (Rugh et al. 

2000b) in that belugas in Cook Inlet tend to be in shallow coastal areas, especially near river 

mouths (such as the Susitna Rivers) and bays (Knik Arm, Turnagain Arm, and Chickaloon Bay). 

 Of the 34 sightings recorded during the monthly surveys, 26 were in the same areas where 

belugas have been found almost every year in June or July. The exceptions were one (tagged) 

whale seen in mid-inlet off the McArthur River on 27 August (Fig. 3); 1-2 whales in Trading 

Bay on 9 November (Fig. 6); all sightings in one small area near the middle of the inlet west of 

Moose Point on 22 January (Fig. 7); and all sightings well offshore west of Point Possession on 2 

April (Fig. 9). Although it is not unusual to find belugas in Turnagain Arm, as recorded in 

August (Fig. 3), September (Fig. 4), and November (Fig. 6), sightings were not common here 

during the spring; only twice were beluga groups seen here even though there were nine flights 
12 

over Turnagain Arm in June 2001 and June 2002 (Rugh et al. 200a and 2000b). The generalized 

locations of beluga sightings are presented in Table 4 relative to the dates of the sightings. 

Other Marine Mammals 

Other than belugas, only harbor seals (Phoca vitulina) were encountered during these 

surveys of upper Cook Inlet. There were six sightings recorded, ranging from 8 to 150 seals. 

Harbor seal concentrations were found at the Susitna Delta (n = 50 on 27 July 2001), in the Little 

Susitna River (n = 150 on 27 July 2001), Chickaloon River (n = 70 on 27 July 2001), Ivan River 

(n = 8 on 27 August 2001), McArthur River (n = 20 on 27 August 2001), and Beluga River (n = 

55 on 18 September 2001). 

Discussion 

The distribution of belugas in Cook Inlet has been well documented by aerial surveys 

conducted during June and July (Rugh et al. 2000b), through local Native knowledge 

(Huntington 2000), and by the tracking of whales with satellite tags (Ferrero et al. 2000; NMFS 

unpubl. data), but relatively little is known about beluga distribution during the winter. The 

aerial surveys described here, flown most months of the year, continued to find belugas in upper 

Cook Inlet (except in February). These observations suggest that at least some whales inhabit 

this area year-round, although their distribution may be more offshore in winter than in summer. 

 On the other hand, beluga counts were very low from November to April (Table 2). This is 

interpreted here as being mostly a function of the difficulty of finding belugas when there is sea 

ice (which was prevalent from November through April, even though NOAA and the US Army 
13 

Corps of Engineer=s Ice Forecast Center indicated it was a light ice year), when the whales are 

offshore doing deep, long dives (NMFS unpubl. data), and when the whales are not grouped near 

in shallow water near river mouths. The drop in sightings in winter is not considered to be 

evidence that these whales leave the area. Hansen and Hubbard (1999) also flew surveys in 

February and March, counting 150 belugas in 10 sightings (including resightings; median = 29) 

mostly in the central parts of the Inlet north of Kalgin Island. Also, a variety of other sources 

have indicated that belugas are seen north of the Forelands throughout the winter (see Rugh et al. 

2000b), including Native hunters (Huntington 2000), sightings from drilling platforms (R. F. 

Dahlheim, Jr., 16126 Dubuque Road, Snohomish, WA 98290. pers. commun.), commercial 

flights across the inlet (R. Priewe, Priewe Air Service, Anchorage, Alaska, pers. commun.), and 

14 whales carrying satellite tags between July and March 2000 to 2003 (NMFS unpubl. data). 

Calkins (1983) concluded that belugas were present in all seasons in the inlet, based on his own 

sightings. The sum of these sightings and records suggest that upper Cook Inlet, north of Kalgin 

Island, may be important habitat for these belugas throughout the year (Fig. 10). 

Acknowledgments 

Funding for this project was provided through the Alaska Regional Office of NMFS and 

through the National Marine Mammal Laboratory. Rod Hobbs (NMML) was task leader of the 

NMFS beluga research project in Cook Inlet. Dave Weintraub (Commander NW, Ltd., 

Wenatchee, WA) piloted the aircraft, sometimes with Randy Weber or Tom Lamby as copilots. 

Dave=s investment in this project is greatly appreciated. Bill Gossweiler flew on all but two of 

the flights, doing videotaping each group of belugas for later analysis. Kate Wedemeyer, Marcus 
14 

Geist, Melanie Wahl, Chantal Walsh, Dan Bogan, Christopher Garner, Kelly Proffitt, Kristin 

Simac, Matthew Eagleton, Josh Peirce, and Danielle Cooley assisted with the survey and made 

the data entries. Counts of belugas in the video were provided by Christy Sims (NMML). The 

survey maps were made by Kim Shelden (NMML). Document reviews were provided by Kim 

Shelden, David Withrow, Rod Hobbs, and Robyn Angliss of NMML, and Gary Duker and James 

Lee of the Alaska Fisheries Science Center Publication Department. This survey was conducted 

under MMPA Scientific Research Permit No. 782-1438 and has been in cooperation with the 

Alaska Beluga Whale Commission (ABWC) and Cook Inlet Marine Mammal Council 

(CIMMC). 

Citations 

Calkins, D. G. 1983. Marine mammals of lower Cook Inlet and the potential for impact from 

Outer Continental Shelf oil and gas exploration, development, and transport. Research 

Unit 243; Final Rep. of Principal Investigators, Outer Continental Shelf Environ. 

Assessment Program, U.S. Dep. Commer., Natl. Oceanic Atmospheric Admin., Natl. 

Ocean Serv., Off. of Oceanogr. Mar. Serv., Ocean Assessments Div. 20:171-263. 

Ferrero, R. C., S. E. Moore, and R.C. Hobbs. 2000. Development of beluga, Delphinapterus 

leucas, capture and satellite tagging protocol in Cook Inlet, Alaska. Mar. Fish. Rev. 

62(3):112-123. 

Hansen, D. J., and J. D. Hubbard. 1999. Distribution of Cook Inlet beluga whales 

(Delphinapterus leucas) in winter. U.S. Dep. Inter., Minerals Manage. Serv., Alaska OCS 

Region, Anchorage Final Rep., OCS Study MMS 99-0024. 
15 

Hobbs, R.C., D.J. Rugh, and D.P. DeMaster. 2000a. Abundance of beluga whales, 

Delphinapterus leucas, in Cook Inlet, Alaska, 1994-2000. Mar. Fish. Rev. 62(3):37-45. 

Hobbs, R.C., J.M. Waite, and D.J. Rugh. 2000b. Beluga, Delphinapterus leucas, group sizes in 

Cook Inlet, Alaska, based on observer counts and aerial video. Mar. Fish. Rev. 62(3):46-

59. 

Huntington, H. P. 2000. Traditional ecological knowledge of beluga whales in Cook Inlet. Mar. 

Fish. Rev. 62(3):134-140. 

Laidre, K. L., K. E. W. Shelden, D. J. Rugh, and B. A. Mahoney. 2000. Beluga, Delphinapterus 

leucas, distribution and survey effort in the Gulf of Alaska. Mar. Fish. Rev. 62(3):27-36. 

Moore, S. E., D. J. Rugh, K. E. Shelden, L. K. Litzky, and B. A. Mahoney. 2000. Beluga, 

Delphinapterus leucas, habitat associations in Cook Inlet, Alaska. Mar. Fish. Rev. 

62(3):60-80. 

O=Corry-Crowe, G.M., R.S. Suydam, A. Rosenberg, K.J. Frost, and A.E. Dizon. 1997. 

Phylogeography, population structure and dispersal patterns of the beluga whale 

Delphinapterus leucas in the western Nearctic revealed by mitochondrial DNA. Mol. 

Ecol. 6:955-970. 

Rugh, D.J., R.P. Angliss, D.P. DeMaster, and B.A. Mahoney. 1995. Aerial surveys of belugas in 

Cook Inlet, Alaska, June 1994. Unpubl. Doc. Submitted to Int. Whal. Comm. 

(SC/47/SM10). 14p. 

Rugh, D.J., K.E.W. Shelden, R.P. Angliss, D.P. DeMaster, and B.A. Mahoney. 1996. Aerial 

surveys of beluga whales in Cook Inlet, Alaska, July 1995. Unpubl. Doc. Submitted to 

Int. Whal. Comm. (SC/48/SM8). 21p. 
16 

Rugh, D.J., K.E.W.Shelden, J.M. Waite, R.C. Hobbs, and B.A.Mahoney. 1997a. Aerial surveys 

of beluga whales in Cook Inlet, Alaska, June 1996. Unpubl. Doc. Submitted to Int. Whal. 

Comm. (SC/49/SM19). 22p. 

Rugh, D.J., R.C. Hobbs, K.E.W.Shelden, and J.M. Waite. 1997b. Aerial surveys of beluga 

whales in Cook Inlet, Alaska, June 1997. Unpubl. Doc. Submitted to Int. Whal. Comm. 

(SC/49/SM20). 17p. 

Rugh, D.J., R.C. Hobbs, K.E.W. Shelden, B.A. Mahoney, and L.K. Litzky. 1999. Surveys of 

beluga whales in Cook Inlet, Alaska, June 1998. Unpubl. Doc. Submitted to Int. Whal. 

Comm. (SC/51/SM11). 11p. 

Rugh, D.J., K.E.W. Shelden, B.A. Mahoney, L.K. Litzky, R.C. Hobbs, and K.L. Laidre. 2000a. 

Aerial surveys of beluga whales in Cook Inlet, Alaska, June 1999, p. 1-10. In A. L. Lopez 

and D.P. DeMaster (eds.), Marine Mammal Protection Act and Endangered Species Act 

Implementation Program 1999. AFSC Processed Report 2000-11. Alaska Fish. Sci. 

Cent., Natl. Mar. Fish Serv., NOAA, 7600 Sand Point Way, NE, Seattle, WA 98115. 

Rugh, D.J., K.E.W. Shelden, and B.A. Mahoney. 2000b. Distribution of belugas, Delphinapterus 

leucas, in Cook Inlet, Alaska, during June/July 1993-2000. Mar. Fish. Rev. 63(3):6-21. 

Rugh, D., K.E.W. Shelden, B.A. Mahoney, and L.K. Litzky. 2001. Aerial surveys of belugas in 

Cook Inlet, Alaska, June 2000, p. 1-11. In A.L. Lopez and R.P. Angliss (eds.), Marine 

Mammal Protection Act and Endangered Species Act Implementation Program 2000. 

AFSC Processed Report 2001-06. Alaska Fish. Sci. Cent., Natl. Mar. Fish Serv., NOAA, 

7600 Sand Point Way, NE, Seattle, WA 98115. 
17 

Rugh, D., K.E.W. Shelden, B.A. Mahoney, and L.K. Litzky. 2002a. Aerial surveys of beluga in 

Cook Inlet, Alaska, June 2001, p. 1-12. In: A.L. Lopez and S.E. Moore (eds.), Marine 

Mammal Protection Act and Endangered Species Act Implementation Program 2001. 

AFSC Processed Report 2002-06. Alaska Fish. Sci. Cent., Natl. Mar. Fish Serv., NOAA, 

7600 Sand Point Way, NE, Seattle, WA 98115. 

Rugh, D., B.A. Mahoney, L.K. Litzky, and B. Smith. 2002b. Aerial surveys of beluga in Cook 

Inlet, Alaska, June 2002. Natl. Mar. Mammal Lab., NMFS, NOAA, 7600 Sand Point 

Way, NE, Seattle, WA 98115. 12 p. 

Rugh, D.J., B.A. Mahoney, C.L. Sims, B.K. Smith, and R.C. Hobbs. 2003. Aerial surveys of 

belugas in Cook Inlet, Alaska, June 2003. Natl. Mar. Mammal Lab., NMFS, NOAA, 

7600 Sand Point Way, NE, Seattle, WA 98115. 13 p. 

Withrow, D.E., K.E.W. Shelden, D.J. Rugh, and R.C. Hobbs. 1994. Beluga whale, 

Delphinapterus leucas, distribution and abundance in Cook Inlet, 1993, p. 128-153. In H. 

Braham and D. DeMaster (eds.), Marine Mammal Assessment Program: Status of stocks 

and impacts of incidental take; 1993. Annual Rept. submitted to Office of Protected 

Resources, NMFS, 1335 East-West Highway, Silver Spring, MD 20910. 
-- 

18 

Table 1. Aerial surveys for belugas in Cook Inlet during 2001 and 2002, showing days between surveys, flight 

hours, and time spent in systematic search (not including time in poor visibility or while circling whales for 

counts). Median counts are from the two primary observers during multiple passes over whales. The 

counts include all groups seen on the respective days, whether on coastal surveys or transects. 

Days since Flight Survey Median 

Date last survey hours hours Comments count 

2001 June 5-12* 54.71 29.4 Entire inlet 211 

A July 2 20 10.25 6.74 Transects + coastal 39 

A July 26 24 4.49 4.27 Transects 

152 

A July 27 1 5.67 4.45 Coastal 

A Aug. 27 31 9.25 6.73 Transects + coastal 205 

A Sep. 15 19 4.25 3.43 Coastal 

185 

A Sep. 18 3 5.05 3.85 Transects 

A Oct. 12 24 5.05 4.37 Transects 

162 

A Oct. 15 3 5.07 4.10 Coastal 

A Nov. 8 24 5.05 4.15 Transects 

24 

A Nov. 9 1 4.50 2.90 Coastal 

2002 Jan. 22 74 3.83 3.27 Transects 

15 

A Jan. 23 1 2.92 2.33 Coastal 

A Feb. 25 33 4.13 3.74 Transects 

0 

A Feb. 26 1 3.25 2.12 Coastal 

A Apr. 2 35 5.03 4.65 Transects 

18 

A Apr. 3 1 3.60 2.50 Coastal 

A June 4-11^ 62 44.65 25.0 Entire inlet 192 

* Reported in Rugh et al. 2002a. 

^

 Reported in Rugh et al. 2002b. 
19 

Table 2. Dates, locations, and counts of belugas in Cook Inlet between July 2001 and April 2002. Numbers in bold 

print were used to summarize monthly medians. 

Date Location Group 

number 

Number 

of passes 

Median 

count 

Max 

count 

Video 

count 

2001 July 2 Beluga River 1 6 16 28 -- 

A East of Susitna River 2 2 3 4 -- 

A Susitna River 3 4 13 17 -- 

A Point Possession 4 2 5 7 4 

A East of Susitna River 5 1 2 2 -- 

2001 July 26 Little Susitna River 1 1 15 15 -- 

2001 July 27 Little Susitna River 1 7 87 100 -- 

A Eagle River (Knik Arm) 2 7 65 89 81 

2001 Aug. 27 Turnagain Arm 1 4 31 46 29 

A Turnagain Arm 2 4 83 113 90 

A Little Susitna River 3 4 16 20 15 

A Point MacKenzie (Knik Arm) 4 1 3 3 -- 

A Knik Arm 5 5 71 94 -- 

A mid-inlet 6 1 1 1 -- 

2001 Sep. 15 Knik Arm 1 1 1 1 -- 

A Eagle River 2 2 7 8 -- 

A Eagle River 3 5 105 115 69 

A Turnagain Arm 4 5 70 107 72 

A Beluga River 5 3 1 2 -- 

A Theodore River 6 1 1 1 -- 

2001 Sep. 18 -- -- 0 0 -- 

2001 Oct. 12 Little Susitna River 1 3 0 3 -- 

2001 Oct. 15 Knik Arm 1 7 155 254 -- 

A Knik Arm 2 1 7 7 -- 

2001 Nov. 9 Turnagain Arm 1 6 3 7 -- 

A Turnagain Arm 2 3 6 11 -- 

A Trading Bay 3 2 1 2 -- 

A North of Eagle Bay (Knik) 4 6 14 98 -- 

 
20 

Table 2 continued. 

2002 Jan. 22 mid-inlet 1 5 6 11 4 

A mid-inlet 2 4 1 6 2 

A mid-inlet 3 1 2 2 -- 

A mid-inlet 4 1 1 1 -- 

A mid-inlet 5 1 5 5 -- 

2002 Jan. 23 mid-inlet -- -- 0 0 -- 

2002 Feb. 25 -- -- 0 0 -- 

2002 Feb. 26 -- -- 0 0 -- 

2002 Apr. 2 west of Point Possession 1 2 8 9 -- 

A west of Point Possession 2 4 10 14 -- 
21 

 Table 3. Comparison of video and observer counts made during aerial surveys of belugas in Cook Inlet. 

Survey Video Mahoney 

ANOVA 

(video-Mahoney) Video Smith 

ANOVA 

(video-Smith) 

June 2001 

0 = 36.3 

SE = 5.2 

n = 60 

0 = 36.5 

SE = 3.7 

n = 60 

P = 0.96 ---- ---- ---- 

Monthly 

surveys 

2001-02 

0 = 44.4 

 SE = 7.5 

n = 32 

0 = 45.9 

SE = 6.3 

n = 32 

P = 0.88 

0 = 45.4 

 SE = 7.5 

n = 32 

0 = 49.5 

SE = 7.2 

n = 32 

P = 0.69 

June 2002 

0 = 17.3 

SE = 4.1 

n = 26 

0 = 24.9 

SE = 5.3 

n = 26 

P = 0.26 

0 = 20.4 

 SE = 5.5 

n = 27 

0 = 28.6 

SE = 7.3 

n = 27 

P = 0.37 

 Table 4. Beluga sightings (median counts) in Cook Inlet as a function of generalized locations and survey date. 

Generalized locations 

2001 

July 

2 

2001 

July 

26-27 

2001 

Aug. 

27 

2001 

Sep. 

15&18 

2001 

Oct. 

12&15 

2001 

Nov. 

9 

2002 

Jan. 

22-23 

2002 

Feb. 

 25-26 

2002 

Apr. 

2 

Susitna area (Beluga R. 

 to Little Susitna R.) 

34 102 16 2 0 0 0 0 0 

Knik Arm 0 65 74 113 162 14 0 0 0 

Turnagain Arm 0 0 114 70 0 10 0 -- 0 

Chickaloon R. to 

Pt. Possession 

2 0 0 0 0 0 0 0 0 

Mid-inlet 0 0 1 0 0 0 15 0 18 

Trading Bay 0 0 0 0 0 1 0 0 0 
22 
 


Figure 1. Tracklines flown on 2 July 2001. Only search areas where visibility was recorded as fair to 

excellent are included. Beluga groups are shown as open circles. Four groups were seen along 

the north side of the inlet and one in Chickaloon Bay, locations typical of beluga summer 

distribution. 

Figure 2. Tracklines flown on 26-27 July 2001. Only search areas where visibility was recorded as fair 

to excellent are included. Beluga groups are shown as open circles. A group was found at the 

mouth of the Little Susitna River on both days, and a large group was seen north of Eagle Bay 

in Knik Arm. 
23 
 


Figure 3. Tracklines flown on 27 August 2001. Only search areas where visibility was recorded as fair to 

excellent are included. Beluga groups are shown as open circles. One group was seen near the 

Little Susitna River, two in Knik Arm, two in Turnagain Arm, and one whale (with a satellite 

tag) was seen mid-inlet near the Forelands. 

Figure 4. Tracklines flown on 15 and 18 September 2001. Only search areas where visibility was 

recorded as fair to excellent are included. Beluga groups are shown as open circles. Two or 

three whales were seen near Beluga River, three groups (one large) were in Knik Arm, and one 

large group was in Turnagain Arm. 
24 
 


Figure 5. Tracklines flown on 12 and 15 October 2001. Only search areas where visibility was recorded 

as fair to excellent are included. Beluga groups are shown as open circles. A few whales were 

seen near the Little Susitna River, but most were in Knik Arm. 

Figure 6. Tracklines flown on 9 November 2001. Only search areas where visibility was recorded as fair 

to excellent are included. Sea ice covered much of the area. Beluga groups are shown as open 

circles. Two small groups were in Turnagain Arm, 1-2 whales were near Trading Bay, and 

most were in Knik Arm, but summary counts were lower than on the previous surveys. 
25 
 


Figure 7. Tracklines flown on 22 and 23 January 2002. Only search areas where visibility was recorded 

as fair to excellent are included. Sea ice covered much of the area. Beluga groups are shown 

as open circles. Five small groups were seen, all of them offshore toward the middle of the 

inlet, atypical of the summer distribution. 

Figure 8. Tracklines flown on 25 and 26 February 2002. Only search areas where visibility was recorded 

as fair to excellent are included. Sea ice covered much of the area. No belugas were seen on 

these flights. 
26 
 


Figure 9. Tracklines flown on 2 April 2002. Only search areas where visibility was recorded as fair to 

excellent are included. Sea ice covered much of the area. Beluga groups are shown as open 

circles. Similar to the January sightings, the only groups that were seen were well offshore 

toward the center of the inlet. 

Fig. 10. Summary map showing locations in Cook Inlet where beluga groups were seen during aerial 

surveys relative to sighting date in 2001-02. 
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